Your first port of call is the red plunger on the right-hand side in the middle of the room. This’ll activate the blue portal in here, so turn back around and walk into the orange portal. You’ll reappear in the section where the Companion Cube is resting.
Now take the Companion Cube back through the orange portal and hit the red plunger switch on the left, take the Cube back through the orange portal behind you and drop the Cube on the large, flat red button.
This’ll open up the exit, so double-back on yourself, press the third - and final - red plunger in the room and make your way back through the portal one final time. Step into the elevator to finish the level.
Welcome back to Aperture Science, a world where your Companion Cube isn't you're only company. Take control of Chell once again in Valve's sequel which takes you on an humorous and puzzling adventure and in our detail-packed guide we'll show you:
How to solve every test chamber first time.
Conquer every co-op chamber with a friend.
Loads of High Definition screenshots and videos showing you the solutions to every single chamber.
High Definition strategy videos for every achievement in the game.
Uncover all of the hidden secrets and Easter eggs.